1. Field of the Invention
The present invention relates to a technique for a substrate processing apparatus. More particularly, the invention relates to a technique for a slit nozzle for discharging a predetermined processing solution toward substrates such as a glass substrate for manufacturing a flat-panel display.
2. Description of the Background Art
The trend in application of a processing solution to a substrate is toward the popularization of scan coating which carries out scanning using a slit nozzle for discharging the processing solution to apply the processing solution to a predetermined position on the substrate.
Some apparatuses which carry out the scan coating comprise a supply pump provided in the slit nozzle and mechanically operative to feed a processing solution, thereby discharging the processing solution from a slit at the tip of the nozzle during the scanning operation.
However, because of the mechanical operation of the supply pump to feed the processing solution, the conventional apparatuses having the pump in the slit nozzle produce a pulsing stream of the processing solution being discharged, which impairs the uniform discharge of the processing solution. Other problems with the conventional apparatuses are as follows. A distance prone to be long from the supply pump to a tapered discharge port causes poor discharging responsiveness. It is difficult to uniformly discharge the solution from a discharge port having the shape of an elongated slit even if there are provided a plurality of supply ports of the solution to the nozzle. The discharge uniformity depends on the finishing accuracy of the nozzle, and the finishing accuracy is not adjustable.